The objective of this investigation was the assessment of the response rate of oral atenolol in patients with vasovagal syncope after 1 month of treatment. We randomized into two groups all patients referred to our unit who had had at least one episode of syncope or two episodes of presyncope 1 month before presentation and had a positive isuprel Tilt Table Test (TTT). Group 1 (Gr 1) received oral atenolol, and group 2 (Gr 2) received placebo medication. After a 1-month period patients were reassessed for degree of their symptoms and underwent repeated TTT. Forty-two patients were enrolled in the study. Gr 1 and Gr 2 were comparable in age (38 +/- 13 years vs 43 +/- 14 years, p = 0.216 and sex (male/female = 6:15 vs 10:11, p = 0.204). The severity of attack was similar in both groups. Eight patients in Gr 1 and six patients in Gr 2 had mitral valve prolapse (p = 0.5). No significant differences were seen in systolic blood pressure (122 +/- 17 vs 117 +/- 16 mmHg, p = 0.334), diastolic blood pressure (70 +/- 11 vs 72 +/- 11 mm Hg, p = 0.677), and heart rate (79 +/- 12 vs 79 +/- 13, p = 0.98) between the two groups. The response rates (negative TTT) after 1 month of treatment were 62% versus 5% (p = 0.0004) in the atenolol and control group, respectively. Moreover, patients who received atenolol reported feeling better compared with those who received placebo (71% vs 29%, p = 0.02). In conclusion, atenolol significantly improved symptoms of patients with vasovagal syncope.(ABSTRACT TRUNCATED AT 250 WORDS)